SSC-3: Discussion related to Letter Ballot SYM-019-a

Kevin D Butt kdbutt at
Thu Jun 19 12:31:36 PDT 2008

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The Keyless copy section should identify How an application 
client determines that a Logical Unit has the capability to act as a KCSLU 
or a KCDLU
There is no bit anywhere that indicates the support for acting as a KCSLU 
or KCDLU.  In reality, it is if the LU supports the EXTERNAL encryption 
mode or the RAW decryption mode.  So the request here should be reworded 
to say how does an application client determine which settings of 
"ENCRYPTION MODE" and "DECRYPTION MODE" fields are supported.
Looking at the section describing each of these fields, there is no text 
describing a CC returned for RAW or EXTERNAL if they are not supported. 
The standard is silent.  This is also the case for DISABLE.  Obviously the 
standard does not explicitly indicate anywhere that these modes are 
What should we do?
Option 1: Add text under the description of these fields stating that if 
EXTERNAL or RAW mode is selected and it is not supported then CC.  This 
would change the standard to explicitly state that these options are 
Option 2: Add text somewhere to mandate support for these modes.  I 
suspect this option is not desired.
I think that we must do either option 1 or option 2.  The standard needs 
to be clear if these are optional or not.
If we go done the path that these are explicitly stated as optional, then 
this letter ballot comment leads to the question, "How do we report 
support for different values in these two fields?"  This is not just a 
question of Keyless copy but also of MIXED decryption mode.  There is an 
implication that ENCRYPT and DECRYPT are supported as well as DISABLE.	I 
am not sure that is correct.  There could be a device that only supportes 
one or the other or some combinations.
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at

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